This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Examine the effects of a 90-minute nap compared to no-nap on a variety of cognitive processes. Test whether prior sleep measured by actigraphy affects the sleep stages in a nap and is correlated with performance. Examine whether habitual napping affects the structure of a nap and performance.